A. Field of the Invention
This invention relates to an audio open reel type tape cassette in which a pair of reels are incorporated, and is particularly concerned with a reel supporting structure permitting both sides of the reel to separate from inside of the cassette half for rotation.
B. Description of the Prior Art
Various types of reproducing equipments are provided for the young music-loving, and particularly cassette tape reproducing equipment has become popular for its portability and also in interdependence with a tape performance further improved recently.
A magnetic performance of the tape itself will be taken up first as a factor to influence a tonal quality obtained through the cassette tape reproducing equipment. However, another essential factor is a stable running capacity of the tape. In other words, a smooth running on a slight torque of the reproducing equipment is essential to improve the tonal quality satisfactorily and also to lighten the mechanical burden of the reproducing equipment body.
In a conventional tape cassette, for example, U.S. Pat. No. 4,248,393 issued on Feb. 3, 1981, a pair of hubs is supported rotatably in a cassette case, and a series of tape is wound on the hubs. However, according to this structure, the hubs are rotated with a side of the wound tape rubbed at all times with an inside of the cassette case. Accordingly, a frictional force to prevent rotations of the hubs works on the pair of hubs all the time, and thus the rotations are not smoothed to deteriorate running performance of the tape. To cope with such defect, there exists an art for bringing sides of the hubs and the tape in contact with a synthetic resin film with less frictional resistance which is interposed inside of the cassette case. However, such art comprises after all permitting the tape and the hubs to rub with the synthetic resin film, and though an absolute value of the frictional force decreases in fact, the hubs still do not run smoothly.
Then, an open reel type tape cassette proposed by the same inventors as this invention has come into wide use recently instead of the conventional tape cassette simply winding the tape on the hubs. The open reel type tape cassette is arranged such that, as disclosed, for example, in Japanese Utility Model Publication No. 72772/1983, a pair of annular projections is formed on the inside of a set of cassette halves, a pair of reels on which a series of tape is wound with a reel hub held between a set of metal flanges mounted on the annular projections, the reel hub is placed in position by the annular projections, and then the reels are rotated to run the tape. Such open reel type tape cassette has become popular for its specific design of providing full-scale reels in the cassette with a limited space and surprising aesthetic appearance, however, the situation that the reels run with the side kept rubbing the inside of the cassette half may unavoidably cause a frictional force.